*Peel and chop one russet potato into small chunks. Boil for 7 - 10 minutes, until very tender, and drain thoroughly. Beat well either with the paddle attachment of your stand mixer, or a potato masher, until completely smooth and lump-free. Do not add any liquid or seasoning. Measure out 1/4 cup and reserve the rest for another use.

**Peppermint oil is much stronger than peppermint extract, and thus the two are not directly interchangeable. If you can't get a hold of the oil, try substituting 3/4 - 1 1/4 teaspoons of extract, to taste, and bear in mind that you will likely need more confectioner's sugar to make up for the added liquid.

Place your mashed potatoes in the bowl of your food processor fitted with the paddle attachment, or in you food processor. Add the margarine and cream the two together until smooth. Incorporate 2 cups of confectioner's sugar to start, along with the vanilla, peppermint oil, and salt. Start on a slow speed, or pulse to combine. The mixture will likely look like thick icing at this point, so add in another cup of confectioner's sugar, and once again mix on low. You're looking for it to become the consistency of soft cookie dough; mailable, but not gooey or drippy. If it still seems to be too loose, mix in up to an additional cup of the sugar, as needed.

Turn the potato candy out onto a silpat or piece of parchment paper, and gently flatten it out to about 1/4 - 1/2 inch in thickness. To prevent sticking, either sprinkle on a very light dusting of confectioner's sugar, or top it with a second silpat or sheet of parchment before taking the rolling pin to it. Stash your candy disk in the fridge for at least 30 minutes before proceeding.

Once chilled, pull out a small shamrock-shaped cookie cutter approximately 1-inch wide. Lay out a second silpat or piece of parchment on top of a baking sheet. Cut out your clovers, and transfer them to the prepared sheet. Gather up the candy scraps, re-roll, and cut again, until you've used all of the dough. Should the dough become too soft and finicky to work with, just toss it back in the fridge for another 15 - 30 minutes, and try once more. Now, stash the whole sheet of cut centers in the freezer for at least 30 minutes before getting to work on the coating.

Place your cocoa butter in a microwave-safe bowl and heat for 1 - 3 minutes, so that it completely liquefies. Meanwhile, mix together the remaining ingredients in a small dish, making sure that they're thoroughly combined and that there are no clumps of matcha. Once the cocoa butter is melted, whisk in the dry ingredients, stirring vigorously to make sure that everything is completely dissolved into the molten fat.

Pull out your semi-frozen mint patties, and dip each into the matcha coating, one at a time. Place them back on the silpat, and watch the coating set up right before your eyes. This top coat is thinner than chocolate, so you may wish to double-dip once the first layer has solidified. If using, quickly sprinkle the decorate sugar over the dipped patties as soon as you set them down.